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        <h2 id="collections模块"><a href="#collections模块" class="headerlink" title="collections模块"></a>collections模块</h2><ul>
<li><code>collections</code>包含了一些特殊的容器，针对Python内置的容器，例如list、dict、set和tuple，提供了另一种选择；</li>
<li><code>namedtuple</code>，可以创建包含名称的tuple；</li>
<li><code>deque</code>，类似于list的容器，可以快速的在队列头部和尾部添加、删除元素；</li>
<li><code>Counter</code>，dict的子类，计算可hash的对象；</li>
<li><code>OrderedDict</code>，dict的子类，可以记住元素的添加顺序；</li>
</ul>
<p><strong>这里主要介绍<code>namedtuple</code></strong></p>
<span id="more"></span>

<h3 id="namedtuple"><a href="#namedtuple" class="headerlink" title="namedtuple"></a><code>namedtuple</code></h3><h4 id="tuple"><a href="#tuple" class="headerlink" title="tuple"></a>tuple</h4><ul>
<li><p><code>tuple</code>元组</p>
<ul>
<li><p>不可变；可迭代。python的<strong>变量实质是引用</strong></p>
</li>
<li><p>拆包</p>
<figure class="highlight python"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br></pre></td><td class="code"><pre><span class="line">tup1 = (<span class="string">&#x27;bgape002&#x27;</span>, <span class="string">&#x27;bgape003&#x27;</span>)</span><br><span class="line">tup2 = (<span class="string">&#x27;bgape002&#x27;</span>, <span class="string">&#x27;bgape003&#x27;</span>, <span class="string">&#x27;002&#x27;</span>, <span class="string">&#x27;003&#x27;</span>)</span><br><span class="line">tup3 = (*tup1, <span class="string">&#x27;002&#x27;</span>, <span class="string">&#x27;003&#x27;</span>)</span><br><span class="line"></span><br><span class="line">n1, n2 = tup1</span><br><span class="line">me, *other = tup2  <span class="comment"># 取出第一个元素，其余的放在一个列表里</span></span><br><span class="line">m1, *m2 = tup1</span><br><span class="line"></span><br><span class="line"><span class="built_in">print</span>(n1, n2)</span><br><span class="line"><span class="built_in">print</span>(me, other)</span><br><span class="line"><span class="built_in">print</span>(m1, m2)</span><br><span class="line"></span><br><span class="line"><span class="string">&quot;&quot;&quot;output</span></span><br><span class="line"><span class="string">bgape002 bgape003</span></span><br><span class="line"><span class="string">bgape002 [&#x27;bgape003&#x27;, &#x27;002&#x27;, &#x27;003&#x27;]</span></span><br><span class="line"><span class="string">bgape002 [&#x27;bgape003&#x27;]</span></span><br><span class="line"><span class="string"></span></span><br><span class="line"><span class="string">(&#x27;bgape002&#x27;, &#x27;bgape003&#x27;, &#x27;002&#x27;, &#x27;003&#x27;)</span></span><br><span class="line"><span class="string"></span></span><br><span class="line"><span class="string">&quot;&quot;&quot;</span></span><br></pre></td></tr></table></figure></li>
<li><p>不可变不是绝对的；一般不建议元组里放入可变对象（如列表）</p>
<figure class="highlight python"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br></pre></td><td class="code"><pre><span class="line">tup = (<span class="string">&#x27;bgape&#x27;</span>, [<span class="string">&#x27;bgape002&#x27;</span>, <span class="string">&#x27;bgape003&#x27;</span>])</span><br><span class="line">tup[<span class="number">1</span>].append(<span class="string">&#x27;001&#x27;</span>)</span><br><span class="line"><span class="built_in">print</span>(tup)</span><br><span class="line"></span><br><span class="line"><span class="string">&quot;&quot;&quot;output</span></span><br><span class="line"><span class="string">(&#x27;bgape&#x27;, [&#x27;bgape002&#x27;, &#x27;bgape003&#x27;, &#x27;001&#x27;])</span></span><br><span class="line"><span class="string"></span></span><br><span class="line"><span class="string">&quot;&quot;&quot;</span></span><br></pre></td></tr></table></figure></li>
</ul>
</li>
<li><p><code>tuple</code>优点</p>
<ul>
<li>性能优化，元组会作为常量在编译时确定，优化程序性能</li>
<li>线程安全</li>
<li>元组可作为<code>dict</code>字典的<code>key</code></li>
<li>拆包特性</li>
</ul>
</li>
</ul>
<h4 id="namedtuple-1"><a href="#namedtuple-1" class="headerlink" title="namedtuple"></a>namedtuple</h4><ul>
<li>可以类似<code>class</code>通过<code>.</code>来访问数据；代码简洁，实现简单</li>
<li>继承了<code>tuple</code>的优点</li>
</ul>
<figure class="highlight python"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br></pre></td><td class="code"><pre><span class="line"><span class="string">&quot;&quot;&quot;namedtuple基础应用</span></span><br><span class="line"><span class="string"></span></span><br><span class="line"><span class="string">&quot;&quot;&quot;</span></span><br><span class="line"><span class="keyword">from</span> collections <span class="keyword">import</span> namedtuple</span><br><span class="line"></span><br><span class="line"><span class="comment"># 定义一个namedtuple类型User，并包含name，sex和age属性。</span></span><br><span class="line">User = namedtuple(<span class="string">&#x27;User&#x27;</span>, [<span class="string">&#x27;name&#x27;</span>, <span class="string">&#x27;sex&#x27;</span>, <span class="string">&#x27;age&#x27;</span>])</span><br><span class="line"></span><br><span class="line"></span><br><span class="line"><span class="comment">#########     创建一个User对象    #############</span></span><br><span class="line">user = User(name=<span class="string">&#x27;Runoob&#x27;</span>, sex=<span class="string">&#x27;male&#x27;</span>, age=<span class="number">12</span>)</span><br><span class="line"></span><br><span class="line"><span class="comment"># 获取所有字段名</span></span><br><span class="line"><span class="built_in">print</span>(user._fields)</span><br><span class="line"></span><br><span class="line"><span class="comment"># 也可以通过一个list来创建一个User对象，这里注意需要使用&quot;_make&quot;方法</span></span><br><span class="line">user = User._make([<span class="string">&#x27;Runoob&#x27;</span>, <span class="string">&#x27;male&#x27;</span>, <span class="number">12</span>])</span><br><span class="line"></span><br><span class="line"><span class="built_in">print</span>(user)</span><br><span class="line"><span class="comment"># User(name=&#x27;user1&#x27;, sex=&#x27;male&#x27;, age=12)</span></span><br><span class="line"></span><br><span class="line"><span class="comment"># 获取用户的属性</span></span><br><span class="line"><span class="built_in">print</span>(user.name)</span><br><span class="line"><span class="built_in">print</span>(user.sex)</span><br><span class="line"><span class="built_in">print</span>(user.age)</span><br><span class="line"></span><br><span class="line"><span class="comment"># 修改对象属性，注意要使用&quot;_replace&quot;方法</span></span><br><span class="line">user = user._replace(age=<span class="number">22</span>)</span><br><span class="line"><span class="built_in">print</span>(user)</span><br><span class="line"><span class="comment"># User(name=&#x27;user1&#x27;, sex=&#x27;male&#x27;, age=21)</span></span><br><span class="line"></span><br><span class="line"><span class="comment"># 将User对象转换成字典，注意要使用&quot;_asdict&quot;</span></span><br><span class="line"><span class="built_in">print</span>(user._asdict())</span><br><span class="line"><span class="comment"># OrderedDict([(&#x27;name&#x27;, &#x27;Runoob&#x27;), (&#x27;sex&#x27;, &#x27;male&#x27;), (&#x27;age&#x27;, 22)])</span></span><br><span class="line"></span><br></pre></td></tr></table></figure>

<figure class="highlight python"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br></pre></td><td class="code"><pre><span class="line"><span class="string">&quot;&quot;&quot;namedtuple的一些便捷使用技巧</span></span><br><span class="line"><span class="string"></span></span><br><span class="line"><span class="string">&quot;&quot;&quot;</span></span><br><span class="line"></span><br><span class="line"><span class="keyword">from</span> collections <span class="keyword">import</span> namedtuple</span><br><span class="line"></span><br><span class="line"></span><br><span class="line"><span class="comment"># User = namedtuple(&#x27;User&#x27;, [&#x27;name&#x27;, &#x27;sex&#x27;, &#x27;age&#x27;])</span></span><br><span class="line">User = namedtuple(<span class="string">&#x27;User&#x27;</span>, [<span class="string">&#x27;name&#x27;</span>, <span class="string">&#x27;sex&#x27;</span>, <span class="string">&#x27;age&#x27;</span>, <span class="string">&#x27;heigh&#x27;</span>])</span><br><span class="line">oTup = (<span class="string">&#x27;Runoob&#x27;</span>, <span class="string">&#x27;male&#x27;</span>, <span class="number">12</span>)</span><br><span class="line">oDict = &#123;<span class="string">&#x27;name&#x27;</span>: <span class="string">&#x27;Runoob&#x27;</span>, <span class="string">&#x27;sex&#x27;</span>: <span class="string">&#x27;male&#x27;</span>, <span class="string">&#x27;age&#x27;</span>: <span class="number">12</span>&#125;</span><br><span class="line"><span class="comment"># user = User(name=&#x27;Runoob&#x27;, sex=&#x27;male&#x27;, age=12)   直接赋值</span></span><br><span class="line">user = User(*oTup, <span class="number">178</span>)    <span class="comment"># 通过元组赋值</span></span><br><span class="line">userD = User(**oDict, heigh=<span class="number">178</span>)    <span class="comment"># 通过字典赋值</span></span><br><span class="line"></span><br><span class="line"><span class="built_in">print</span>(user)</span><br><span class="line"><span class="built_in">print</span>(userD)</span><br><span class="line"></span><br><span class="line"><span class="comment"># 拆包特性</span></span><br><span class="line">name, sex, *other = user</span><br><span class="line"><span class="built_in">print</span>(name, sex, *other)</span><br><span class="line"></span><br><span class="line"></span><br><span class="line"><span class="string">&quot;&quot;&quot;output</span></span><br><span class="line"><span class="string">User(name=&#x27;Runoob&#x27;, sex=&#x27;male&#x27;, age=12, heigh=178)</span></span><br><span class="line"><span class="string">User(name=&#x27;Runoob&#x27;, sex=&#x27;male&#x27;, age=12, heigh=178)</span></span><br><span class="line"><span class="string">Runoob male 12 178</span></span><br><span class="line"><span class="string"></span></span><br><span class="line"><span class="string">&quot;&quot;&quot;</span></span><br></pre></td></tr></table></figure>



<h3 id="defaultdict"><a href="#defaultdict" class="headerlink" title="defaultdict"></a><code>defaultdict</code></h3><p>咋觉着基础的<code>dict</code>更灵活好用呢……</p>
<h3 id="deque"><a href="#deque" class="headerlink" title="deque"></a><code>deque</code></h3><p>双端队列，适用于数据需要对头部做频繁操作的情景。</p>
<h3 id="Counter"><a href="#Counter" class="headerlink" title="Counter"></a><code>Counter</code></h3><figure class="highlight python"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br></pre></td><td class="code"><pre><span class="line"></span><br><span class="line"></span><br><span class="line"><span class="keyword">from</span> collections <span class="keyword">import</span> *</span><br><span class="line"></span><br><span class="line"></span><br><span class="line"><span class="keyword">class</span> <span class="title class_">Collections_op</span>(<span class="title class_ inherited__">object</span>):</span><br><span class="line">    <span class="comment"># counter可以支持方便、快速的计数</span></span><br><span class="line">    <span class="keyword">def</span> <span class="title function_">counterop</span>(<span class="params">self</span>):</span><br><span class="line">        cnt1 = Counter()</span><br><span class="line">        cnt2 = Counter(<span class="string">&quot;serchingFortheoceans&quot;</span>)</span><br><span class="line">        cnt3 = Counter(&#123;<span class="string">&quot;dogs&quot;</span>: <span class="number">4</span>, <span class="string">&quot;cats&quot;</span>: <span class="number">8</span>&#125;)</span><br><span class="line">        cnt4 = Counter(a=<span class="number">2</span>,b=<span class="number">4</span>,c=<span class="number">0</span>,d=-<span class="number">2</span>,e = <span class="number">1</span>,g=<span class="number">2</span>,f=<span class="number">4</span>,h=<span class="number">2</span>)</span><br><span class="line">        cnt5 = Counter(a=<span class="number">5</span>, b=<span class="number">1</span>, c=<span class="number">2</span>, d=<span class="number">1</span>, e=<span class="number">1</span>, g=<span class="number">4</span>, h=<span class="number">2</span>, j=<span class="number">4</span>)</span><br><span class="line">        wordList = [<span class="string">&quot;a&quot;</span>, <span class="string">&quot;b&quot;</span>, <span class="string">&quot;c&quot;</span>, <span class="string">&quot;c&quot;</span>, <span class="string">&quot;a&quot;</span>, <span class="string">&quot;a&quot;</span>]</span><br><span class="line">        <span class="keyword">for</span> word <span class="keyword">in</span> wordList:</span><br><span class="line">            cnt1[word] += <span class="number">1</span></span><br><span class="line">        <span class="built_in">print</span>(cnt1, <span class="built_in">type</span>(cnt1))</span><br><span class="line">        <span class="built_in">print</span>(cnt2, <span class="built_in">type</span>(cnt2))</span><br><span class="line">        <span class="built_in">print</span>(<span class="string">&quot;-&quot;</span> * <span class="number">20</span>)</span><br><span class="line">        <span class="built_in">print</span>(cnt3, <span class="built_in">type</span>(cnt3))</span><br><span class="line"></span><br><span class="line">        <span class="comment"># Counter对象类似于字典，如果某个项缺失，会返回0，而不是报出KeyError</span></span><br><span class="line">        <span class="built_in">print</span>(<span class="string">&#x27;s:&#x27;</span>,cnt2[<span class="string">&#x27;s&#x27;</span>],<span class="built_in">type</span>(cnt2[<span class="string">&#x27;s&#x27;</span>]),<span class="string">&#x27;dogs:&#x27;</span>,cnt3[<span class="string">&#x27;dogs&#x27;</span>],<span class="string">&#x27;dog:&#x27;</span>,cnt3[<span class="string">&#x27;dog&#x27;</span>])</span><br><span class="line">        <span class="comment"># 元素赋值与删除元素</span></span><br><span class="line">        cnt3[<span class="string">&#x27;dog&#x27;</span>] = <span class="number">0</span></span><br><span class="line">        <span class="keyword">del</span> cnt3[<span class="string">&#x27;dogs&#x27;</span>]</span><br><span class="line">        <span class="built_in">print</span>(<span class="string">&#x27;cnt3:&#x27;</span>, cnt3)</span><br><span class="line">        <span class="built_in">print</span>(<span class="string">&#x27;-&#x27;</span>*<span class="number">40</span>)</span><br><span class="line">        <span class="built_in">print</span>(<span class="string">&#x27;cnt4:&#x27;</span>, cnt4)</span><br><span class="line"></span><br><span class="line">        <span class="comment"># element()，返回一个迭代器，每个元素重复的次数为它的数目，</span></span><br><span class="line">        <span class="comment"># 顺序是任意的顺序，</span></span><br><span class="line">        <span class="comment"># 如果一个元素的数目少于1，那么elements()就会忽略它；</span></span><br><span class="line">        <span class="built_in">print</span>(<span class="string">&#x27;cnt4.elements:&#x27;</span>,<span class="built_in">list</span>(cnt4.elements()))</span><br><span class="line"></span><br><span class="line">        <span class="comment"># most_common(n)，返回一个列表，包含counter中n个最大数目的元素，</span></span><br><span class="line">        <span class="comment"># 如果忽略n或者n=None，most_common()将会返回counter中的所有元素，</span></span><br><span class="line">        <span class="comment"># 元素有着相同数目的将会以任意顺序排列；</span></span><br><span class="line">        <span class="built_in">print</span>(<span class="string">&#x27;cnt4.most_common:&#x27;</span>, cnt4.most_common(<span class="number">3</span>))</span><br><span class="line"></span><br><span class="line">        <span class="comment"># subtract()，从一个可迭代对象中或者另一个映射（或counter）中，元素相减，</span></span><br><span class="line">        <span class="comment"># 返回一个counter对象，按数值从大到小排序的，</span></span><br><span class="line">        <span class="comment"># 输入和输出都有可能为0或者为负；</span></span><br><span class="line">        <span class="built_in">print</span>(<span class="string">&#x27;-&#x27;</span> * <span class="number">40</span>)</span><br><span class="line">        <span class="built_in">print</span>(<span class="string">&#x27;cnt5:&#x27;</span>, cnt5)</span><br><span class="line">        <span class="built_in">print</span>(<span class="string">&#x27;cnt4:&#x27;</span>, cnt4)</span><br><span class="line">        cnt5.subtract(cnt4)</span><br><span class="line">        <span class="built_in">print</span>(<span class="string">&#x27;cnt5-cnt4:&#x27;</span>, cnt5)</span><br><span class="line"></span><br><span class="line">        <span class="comment"># update()，从一个可迭代对象中或者另一个映射（或counter）中所有元素相加，</span></span><br><span class="line">        <span class="comment"># 是数目相加而非替换它们，</span></span><br><span class="line">        <span class="comment"># 可迭代对象是一个元素序列，而非(key,value)对构成的序列；</span></span><br><span class="line">        <span class="built_in">print</span>(<span class="string">&#x27;cnt5+cnt4:&#x27;</span>, cnt5+cnt4)</span><br><span class="line"></span><br><span class="line"></span><br><span class="line"><span class="keyword">if</span> __name__ == <span class="string">&quot;__main__&quot;</span>:</span><br><span class="line">    op = Collections_op()</span><br><span class="line">    op.counterop()</span><br></pre></td></tr></table></figure>



<h3 id="OrderedDict"><a href="#OrderedDict" class="headerlink" title="OrderedDict"></a><code>OrderedDict</code></h3><h3 id="ChainMap"><a href="#ChainMap" class="headerlink" title="ChainMap"></a><code>ChainMap</code></h3><h3 id="参考链接"><a href="#参考链接" class="headerlink" title="参考链接"></a>参考链接</h3><font size=2>

<p>[1] <a target="_blank" rel="noopener" href="https://www.imooc.com/learn/934">python必学模块-collections</a></p>
<p>[2] <a target="_blank" rel="noopener" href="https://www.runoob.com/note/25726">Python namedtuple</a></p>
<p>[] <a href=""></a></p>
<p></font>&gt;</p>

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